The present invention relates to a composition containing tetrahalophthalate plasticizer admixed with a halogenated resin. This invention also comprehends the method of improving the flame retardancy of a halogenated resin by using tetrahalophthalate plasticizers.
Although polyoxyalkylene tetrahalophthalates are known in the prior art for flame proofing materials, no teachings were found of using this material as a plasticizer or a flame retardant for halogenated resins such as polyvinyl halides. U.S. Pat. No. 4,098,704 describes the use of polyoxyalkylene tetrahalophthalates as flame retardant finishes for 100% polyester fabrics. This is an entirely different application than from that of the instant invention which is related to the plasticization of halogenated resins. The compositions of this invention are prepared to obtain a proper balance between flame retardancy and plasticization properties and yet provide lower smoke values on combustion. U.S. Pat. Nos. 4,094,850 and 2,525,961 and British Pat. No. 1,505,450 describe the use of haloalkyl esters of phthalates as flame retardant plasticizers for resins including PVC. These compositions have the disadvantage of containing labile aliphatic bromine groups which tend to give discolored resins more easily upon heat processing. These compositions are also more expensive since they require the use of not readily available bromoalcohols to form the diesters.